Pierre Lachenay is a well-known publisher and lecturer, married to Franca, with a young daughter, Sabine. On a business trip to Lisbon, he meets an air hostess, Nicole, to whom he is instantly attracted. Lachenay and Nicole start a love affair, which they continue in secrecy when they return to Paris. Later, Lachenay asks Nicole to accompany him to Reims, where he has to give a lecture. In trying to keep their affair a secret from his acquaintances, Lachenay goes too far and Nicole is upset. To make up, the two lovers spend a day in a country hotel – a treat which Lachenay had earlier promised to his wife. When Lachenay's wife discovers what has been happening, she is furious and decides to take a brutal revenge on her husband.